linux-kernel - Re: [PATCH V2] xen: Enable interrupts when calling _cond

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Date:   Wed, 19 Feb 2020 19:42:29 +0100
From:   Jürgen Groß <jgross@...e.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        xen-devel@...ts.xenproject.org
Subject: Re: [PATCH V2] xen: Enable interrupts when calling _cond_resched()

On 19.02.20 18:30, Thomas Gleixner wrote:
> xen_maybe_preempt_hcall() is called from the exception entry point
> xen_do_hypervisor_callback with interrupts disabled.
> 
> _cond_resched() evades the might_sleep() check in cond_resched() which
> would have caught that and schedule_debug() unfortunately lacks a check
> for irqs_disabled().
> 
> Enable interrupts around the call and use cond_resched() to catch future
> issues.
> 
> Fixes: fdfd811ddde3 ("x86/xen: allow privcmd hypercalls to be preempted")
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

Reviewed-by: Juergen Gross <jgross@...e.com>


Juergen